Field of the Invention
The present invention relates to a processing device that binds a sheet bundle carried out from an image forming device such as a copier or a printer and, more particularly, to a technology that prevents the sheet bundle from remaining opened for security purpose.
Description of the Related Art
There are widely known processing devices that align sheets carried out from an image forming device and staple-binds them. Further, there is disclosed a device that temporarily binds the sheet bundle so that others can not easily see contents of the bound sheet bundle.
For example, Jpn. Pat. Appln. Laid-Open Publication No. 2009-51661 discloses a device that staple-binds one end side of a sheet bundle composed of long sheets and short sheets sandwiched between the long sheets and placed on a device tray and half-punches an end portion of the long sheets on an opposite side to the staple-binding portion. When the thus half-punched long sheets are once separated from each other, it is difficult to bind them once again. That is, the half-punch binding can be used as temporary binding for preventing others from easily see contents of the sheet bundle and is effective as a security measure.
However, in the device disclosed in Jpn. Pat. Appln. Laid-Open Publication No. 2009-51661, although the above security measure using the temporary binding can be applied to so-called end surface binding that binds one end of the sheet bundle, it is not applied to so-called saddle-stitching that binds the sheet bundle at its center portion and then folds the bound sheet bundle with the bound portion as a folding position.